Engine Displacement

You get additional capacity of about 20cc over the 4 cylindres, or less than 1% increase.

HTH

DaveP

Steve

On or around Wed, 19 Oct 2005 18:05:44 +0100, Steve enlightened us thusly:

I think he means 40. I thought you could take the 2¼ out to 60 thou', mind...

apparently it's possible to bore out a 499cc Norton single to make it over

It goes from 2286cc to 2337cc if one approximates .040" as being 1mm.

You can get 60thou oversize, but Landrover reccomended 40thou as the maximum overbored on a 2.25. Hence it's more difficult to get the rings/pistons for 60thou.

Let's face it, if you're plumping for 60thou oversize then either it's on it's second rebore or it was very badly damaged/worn in the first place. Worth considering a new engine......

Alex

Thanks guys i meant 40 thous just unsure how to write it. the motor was like that when i got it only found out when i rebuilt the thing

Adam

Thanks mate

I would be grateful if you could also provide us with the calculating formula for the engine dispacement.

TIA Pantelis

For a 4 cylinder engine

bore * bore * stroke * 3.1416 / 1000

gives capacity in cc if bore and stroke are mm.

Double it for 8 cyl, multiply by 1.5 for 6 cyl .... etc, etc.

Or for the mathematical purists

(bore/2)^2 * pi * stroke * no of cyls / 1000

How do you work it out?

Just wondering about my car, into which im currently fitting 1mm oversive pistons.

See my later post in response to the same question from Pantelis.

Thanks, I need to press the 'get new headers' button more before i post. Looks like my car has gone from 1985cc to 2029cc. An increase of 2.2% i reckon. That might give me an extra horse or two! ;)

In news: snipped-for-privacy@news.eftel.com, Adam Bryce blithered:

You're going to get some biiiig engines with your fist version 4* So this example would've been a 9l rather than a 2 1/4. Mathematical one looks OK.

On or around Thu, 20 Oct 2005 10:26:29 -0000, "GbH" enlightened us thusly:

unless you write 0.040" which is unambiguous, and tells a scientist at least that you mean 0.0395

Thank you VERY much.

Thinking about it is must be the formula for the calculation of a cylinder's capacity multiplied by four (for a four pot) or 8 (for a V8) etc.

But the easy way you quoted first is extremely handy.

Thanks aga> > I would be grateful if you could also provide us with the calculating

On or around Thu, 20 Oct 2005 19:34:44 +0300, "Pantelis Giamarellos" enlightened us thusly:

very minor point: you're calculating swept volume, which doesn't take into account the volume, if any, of combustion chamber in the head.

The RAC used to have a formula for "horsepower" which didn't take cylinder stroke into account; since this used to be used for tax rating the motor, it led to all the old long-stroke motors.

and if you happen to want to know the theoretical horsepower of a reciprocating steam engine, it's:

P.L.A.N/33000.

Where P = working pressure, L = cylinder length, A = cylinder area and N = number of working strokes per minute, I think. or maybe per second.

Check the maths on the first one - it works just fine for a 4 cylinder engine. It's the one they teach dumb apprentice automotive machinists because it's less mentally taxing to use.

If you think about it.... bore/2 is 1/2 * bore

when you square this you get (1/2 * 1/2) = 1/4

and bore * bore = bore^2

so if you leave the 1/2 out of the equation for displacement of a single cylinder you have the displacement of a 4 cylinder engine.

Simple, and it's correct.

And strangely enough that's the way all IC engine displacements are calculated and stated. You only need to know CC volume if you want to calculate compression ratios.

I don't need to know it's HP but I would like a hand next weekend to light a wee fire in the thing shown in the link below. Dealing with stuff like this keeps me remembering how technologically advanced a series LR is.